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View Full Version : Has anyone tested GH1 for "flash-band" artifacts?



Peter J. DeCrescenzo
04-30-2009, 05:59 PM
If this question has already been discussed here in these GH1 forums, my apologies. (If so, link please?)

Has anyone tested the GH1 to see if it records CMOS "flash-band" artifacts? (Flash-band artifacts are partially-exposed frames resulting from bright short-duration flashes of light such as from camera flashes, strobe lights, etc.)

Are there example GH1 videos online which show this (if the problem exists)? If the problem exists, is it affected by recording in different modes (e.g.: 1080p24 vs. 720p60, etc.), shutter speed, etc.?

Panasonic recently announced a firmware fix for the HPX300's flash-band artifacts, but I don't know if they've already addressed this CMOS "tendency" in the GH1 or not.

Again, apologies if this issue has already been discussed. Thanks!

Gweilo66
04-30-2009, 06:06 PM
If the Jello AND flash banding are fixed....hopefully the tech will be shared with Panny's other MOS (video)cameras.

(Looks like Pete's ready to battle the flu porcine.)

Kholi
04-30-2009, 06:10 PM
No, but you raise a good point: I can't get the strobe from Vapor or Fluo's out of my footage no matter what shutter I'm at.

=T

Peter J. DeCrescenzo
04-30-2009, 06:21 PM
Kholi: Testing for flash-band is pretty easy. Just point a digital still cam with it's flash activated at the GH1 while the GH1 is recording and take a bunch of flash pics "at" the GH1. Move the "flashing" cam around in the frame to see if it makes any difference. Imagine the GH1 is at an event and camera flashes are going off. How does the 'MOS sensor & processor in the GH1 react to that?

Flash-bands are white, horizontal stripes of varying in height, but which usually don't obscure an entire frame (the way you'd expect a flash to.)

Be sure to look at playback on an external monitor because the GH1's VF/LCD might display something different than what's actually being recorded. (This is true of skew, too.) Thanks!

DavidNJ
04-30-2009, 06:35 PM
The HPX300 has a firmware fix/workaround this summer.

Peter J. DeCrescenzo
04-30-2009, 06:57 PM
The HPX300 has a firmware fix/workaround this summer.

Yes, I referred to this in my earlier post.

I'm wondering if Panasonic maybe has implemented a solution in the GH1 already for this 'MOS tendency -- or not.

Nektonic
04-30-2009, 07:42 PM
This is another reason why I am not so sure that a vDSLR is ready for event work.

Oh, and Kholi, selling the Hague already? What is the skinny on that? I ask because I was looking at one as a possible piece of gear to use with a GH1, and my HV20.

Peter J. DeCrescenzo
04-30-2009, 08:16 PM
This is another reason why I am not so sure that a vDSLR is ready for event work. ...

I raised the question because I don't know whether the GH1 has this issue or not. :shocked:

The GH1 might be fabulous for event work (e.g.: including camera flashes, strobes, etc.), especially if it doesn't record flash-band artifacts.

But someone needs to test for/confirm this for us.

Peter J. DeCrescenzo
05-01-2009, 09:37 AM
Kholi: Testing for flash-band is pretty easy. Just point a digital still cam with it's flash activated at the GH1 while the GH1 is recording and take a bunch of flash pics "at" the GH1. Move the "flashing" cam around in the frame to see if it makes any difference. Imagine the GH1 is at an event and camera flashes are going off. How does the 'MOS sensor & processor in the GH1 react to that?

Flash-bands are white, horizontal stripes of varying in height, but which usually don't obscure an entire frame (the way you'd expect a flash to.)

Be sure to look at playback on an external monitor because the GH1's VF/LCD might display something different than what's actually being recorded. (This is true of skew, too.) Thanks!

Bump. Kholi, Hunter, Phil, anyone? This test will take just a few minutes. Thanks!

Hunter Hampton
05-01-2009, 10:01 AM
Just checked. Yes it does the same thing most cmos cameras do. It has the flashband.

Peter J. DeCrescenzo
05-01-2009, 10:33 AM
Just checked. Yes it does the same thing most cmos cameras do. It has the flashband.

OK, thanks Hunter! Good to know.

Not unexpected, but another data point along the way.

At this point there's no way to know if Panasonic could or would issue a firmware fix for this (or if the GH1's internal circuitry can support this work-around as the HPX-300 apparently can.)

As someone mentioned, it might be possible to deal with the flash-bands in post using a specially-written plugin, but I don't know if one already exists, regrets.

Thanks again!

LizaWitz
05-01-2009, 02:25 PM
Just checked. Yes it does the same thing most cmos cameras do. It has the flashband.

Aliasing? Rolling Shutter? Partial Exposure? Lens so slow you need lights measured in kilowatts? This camera only produces footage that's unusable! :crybaby:

http://i341.photobucket.com/albums/o397/jackcabbage/Slumdog2-6in.jpg

I can't wait to buy it.

dunpeal
11-07-2010, 09:00 PM
I don't have a flash camera to try it but can you perhaps record mjpeg at 720/60fps and eliminate the flash-banding ?